香港大学蔡植豪教授科研团队在Nature Communications期刊发表题为“Device deficiency and degradation diagnosis model of Perovskite solar cells through hysteresis analysis”的研究论文，团队成员王子帅为论文第一作者，蔡植豪、黄志祥研究员为论文通讯作者。
核心亮点：本文提出一种使用定制的含离子漂移-扩散模拟器，全面研究钙钛矿太阳能电池（PSCs）电流密度-电压（J-V）磁滞特征与关键设备问题之间关系的方法，并推导出设备退化的根本原因，为解决和优化PSCs的操作稳定性提供一种新的思路和方法。
磁滞行为是钙钛矿太阳能电池（PSCs）的一个独特而重要的特征，这是由于钙钛矿薄膜内移动离子的缓慢动力学所致。其产生不确定的电池电流密度-电压 ( J-V )曲线，具体取决于电压扫描协议。J-V特性提供了有关器件特性的丰富信息，例如，可以通过研究严重的S形J-V曲线来研究接触层中的缺陷。然而，大多数测量的J-V曲线并没有显示出像S形这样明显的特征，从而无法直接诊断器件性能。
基于前人对PSCs J-V特性研究的基础上，已经确定了太阳能电池的效率损失因素，并描述了辐射和非辐射复合、串联和分流电阻以及接触质量。但是，这些工作可以诊断太阳能电池的瓶颈问题（包括体/表面复合损失，界面能量排列和载流子迁移率），却忽略了PSCs中独特且重要的离子迁移引起的磁滞。有趣的是，由于器件的磁滞将受离子迁移与各种器件缺陷之间的相互作用的控制，J-V磁滞特征将揭示有关器件的隐藏信息（例如用于电场调节、复合和运输的离子迁移）。因此，我们有希望通过简单分析磁滞特性来快速揭示器件物理特性。此外，除识别设备缺陷外，了解衰减的来源对于制造更稳定的设备也非常重要。
在本次研究中，科研人员提出并建立了一个高效的定制漂移扩散模拟器，能够全面研究不同的J-V磁滞特性与器件缺陷之间的关系，例如钙钛矿表面和体内缺陷引起的损耗以及层的低载流子迁移率。实验结果表明，通过J-V迟滞分析可以诊断设备缺陷，例如，具有特定迟滞特征的设备被诊断为遭受大量SHR复合，可能还伴有钙钛矿体区域的低载流子迁移率，这些问题应归因于薄膜质量和体缺陷。对于表现出Type D特征的设备，可以指出设备在界面处经历大量表面复合，由于表面缺陷，这可以通过表面钝化来消除。对于表现出Type E特征的设备，建议设备问题存在于体和界面。对于Type F，建议它可以起源于体复合以及与低效的载流子提取有关。通过比较相同电压扫描速率下的迟滞曲线，还可以评估体或表面复合在设备中的影响。
Fig. 1 | Simulated hysteresis characteristics. a, b, c bulk recombination effect dependent hysteresis characteristics. d surface recombination dependent hysteresis characteristics. e, f synergetic effects induced hysteresis characteristics. “F” and “R” refer to forward and reverse voltage scans, respectively. The schematic diagram of simulated device configuration is inserted in (a).
Fig. 2 | Simulated hysteresis of the high-performance PSCs with different voltage scan rates and FR protocol. a device configuration diagram of simulated n-i-p PSC.
b scan rates dependent JV characteristics of PSC, where “Ref” refers to the reference device without mobile ion.
Fig. 3 | Simulated hysteresis originated from the dominated SRH recombination in perovskite bulk. a τSRH of 1 ns and (b) 10 ns. The simulated transient E-field in the middle of perovskite bulk vs applied voltage compared with the corresponding hysteresis curves of (c) 0.1 V/s and (d) 10 V/s scan in (a). “Ref” refers to the reference device without mobile ion. e, f the position-dependent potential and bulk recombination profiles under a bias of 0.8 V, respectively.
Fig. 4 | Simulated hysteresis originated from the dominated surface recombination. The interfaces recombination between perovskite and CTLs with (a) τsurf = 10 ns and (b)τsurf = 1 ns. The simulated transient E-field at perovskite/HTL interface vs applied voltage compared with the corresponding hysteresis curves of (c) 0.1 V/s and (d) 1 V/s in (a). “Ref” refers to the reference device without mobile ion.
Fig. 5 | Simulated hysteresis originated from low conductivity. a mobility of perovskite is μn(p) = 0.02 cm2 /Vs and (b) mobility of ETL is μn = 2 *10−5 cm2 /Vs.
Fig. 6 | Simulated hysteresis originated from surface and bulk recombination. a τSRH = 100 ns, τsurf = 10 ns and (b) τSRH = 10 ns, τsurf = 10 ns.
Fig. 7 | Comparison of the experimental and theoretical performances of the of PSCs with a large voltage loss. a experimental J–V hysteresis curves of the PSCs before and after the surface passivation treatment. b simulated J–V hysteresis curves of the PSCs with the same scan protocol as in experiments. The term “Control-F/R” denotes the control device under forward/reverse scan, respectively.
Fig. 8 | Comparison of the experimental and theoretical performances of PSCs suffering from degradation of perovskite bulk. a experimental J–V hysteresis curves of the PSCs before and after 300 h’ operation test. b simulated J–V hysteresis curves of the PSCs with the same scan protocol as in experiments.
本文来源：DOI: 10.1038/s41467-024-53162-z
https://doi.org/10.1038/s41467-024-53162-z